Wireless communication system, wireless communication apparatus and wireless communication method and computer program

• US 8,391,257 B2
• Filed: 12/15/2008
• Issued: 03/05/2013
• Est. Priority Date: 02/03/2003
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sakoda, Kazuyuki
• Primary Examiner(s): TRAN, PHUC H
• Application Number:
  US12/335,171
• Publication Number:
  US 20090097464A1
• Time in Patent Office: 1,541 Days
• Field of Search: 370250-253, 370310-3102, 370/338, 370/400
• US Class Current: 370/338
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04W 16/00 Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In order to solve problems arising when a communication system such as a wireless LAN is constructed as a decentralized distributed type network without a relationship of control station and controlled stations such as a master station and slave stations, in a wireless communication system composed of a plurality of communication stations without a relationship of control station and controlled stations, respective communication stations transmit beacons with information concerning a network written thereon with each other to construct the network, and it becomes possible to make sophisticated judgment such as communication states of other communication stations by those beacons.

Claims

1. A wireless communication system comprising:

a plurality of communication stations, wherein

each of said plurality of communication stations is configured to transmit a beacon according to predetermined timing so as to construct a network,

each beacon including neighboring beacon information pertaining to beacon transmission times of neighboring communication stations,

each of said plurality of communication stations having a controller configured to determine a beacon transmission time based on neighboring beacon information obtained from a beacon signal of another station receivable by respective of the plurality of communication stations.

2. The wireless communication system according to claim 1, wherein each communication station connected to said network transmits a beacon signal at a predetermined time interval.

3. The wireless communication system according to claim 2, wherein each of said plurality of communication stations is configured to continuously execute a receiving operation longer than said predetermined time interval at least once during said transmission frame.

4. The wireless communication system according to claim 1, wherein said neighboring beacon information includes information indicative that a particular station will receive a beacon signal transmitted at a particular time.

5. The wireless communication system according to claim 4, wherein any of said plurality of communication stations that has derived a beacon transmission schedule time from a beacon signal of another station by referencing an internal clock value, transmits information to disable a transmission from neighbor stations for a certain time period.

6. The wireless communication system according to claim 4, wherein said neighboring beacon information includes information indicated by a relative time with respect to an internal timer value.

7. The wireless communication system according to claim 1, wherein:

each of said plurality of communication stations is configured to

receive a beacon signal of another station over a certain period of time before starting a new beacon signal transmission,

hold reception time information of a received beacon signal transmitted from another station as first information, and

hold, as second information, by shifting based on said first information, the neighboring beacon information indicative that the respective communication station is recognizing a beacon signal to be transmitted at a particular time carried by said received beacon signal.

8. The wireless communication system according to claim 7, wherein:

when a reception time of a beacon receivable by at least one of the respective communication station and another station is described by said second information, a time section bounding a beacon interval in which an interval between adjacent beacon reception times is maximized and determined to be a target section, and a beacon transmission time of the respective communication station is set to about a center time in said target section, said target section being a time interval between a largest time gap between any two beacons closest in time within a transmission frame.

9. The wireless communication system according to claim 1, wherein each of said plurality of communication stations is configured to attempt reception of a signal transmitted from another station in a predetermined period of time and hold a time zone in which a repetition rate for receiving a beacon and other signals is low, relative to a minimum beacon spacing, and characterized as beacon interval dispersivity information.

10. The wireless communication system according to claim 9, wherein beacon interval information is extracted, and, of time sections having long beacon intervals, a section equivalent to a time zone in which a repetition rate of receiving a signal from said beacon interval dispersivity information is determined to be a target section, setting a beacon transmission time of the respective station to a center time in said target section, said target section being a time interval between a largest time gap between any two beacons closest in time in a transmission frame.

11. The wireless communication system according to claim 1, wherein a communication station that has received a message for requesting a change of beacon transmission time from another station is configured to determine a new beacon transmission time.

12. The wireless communication system according to claim 11, wherein the neighboring beacon information indicative of reception of a beacon signal to be transmitted at a particular time is indicated by a relative time with respect to an internal timer value.

13. The wireless communication system according to claim 11, wherein a particular time zone in which said beacon signal is transmitted is a transmission disabled time section.

14. A wireless communication apparatus comprising:

a communication station configured to communicate in a wireless network with other communication stations, wherein

said communication station includes

a transmitter, and

a controller that is configured to control a transmission operation of said transmitter, wherein said transmission operation includes transmitting a beacon according to predetermined timing so as to construct the wireless network with the other communication stations, and

said beacon including neighboring beacon information pertaining to beacon transmission times of neighboring communication stations, wherein

each of said communication stations determines a beacon transmission time based on neighboring beacon information obtained from a beacon signal of another station.

15. The wireless communication apparatus according to claim 14, wherein the transmission time of a beacon signal to be transmitted from a particular communication station in said network is changed from a predetermined target beacon transmission time by a random time.

16. The wireless communication apparatus according to claim 15, wherein, having recognized reception of a beacon transmission schedule time from another station, said transmitter transmits information for disabling a transmission from a peripheral station for a certain period of time by referencing an internal clock value.

17. The wireless communication apparatus according to claim 15, wherein, having received a beacon from another communication station, said controller computes said target beacon transmission time of each communication station that transmitted a beacon by considering a time indicative of a change from a beacon receiving time.

18. The wireless communication apparatus according to claim 15, wherein, if transmitting a beacon by delaying a beacon transmission time due to an external input, each of said other communication stations includes the delay when transmitting said beacon therefrom.

19. The wireless communication apparatus according to claim 15, wherein

a random time for delaying said transmission time from said target beacon transmission time is given by a pseudo-random sequence, and

a state of the pseudo-random sequence is transmitted as information indicative of a delay carried in said beacon.

20. The wireless communication apparatus according to claim 19, wherein each of said other communication stations holds the state of the pseudo-random sequence to be included in said beacon and updates the pseudo-random sequence when computing a next beacon transmission time of said beacon transmitting station.

21. The wireless communication apparatus according to claim 14, wherein, if a difference is found between a target beacon transmission time of a peripheral station estimated from a clock value derived from a clock held in said communication station and a time at which a beacon is actually received, the clock of the communication station is adjusted by matching said clock with a timing of another station.

22. The wireless communication apparatus according to claim 14, wherein, if a difference is found between a target beacon transmission time of a peripheral station estimated from a clock value derived from a clock held in the communication station and a time at which a beacon is actually received, a timing of another station is adjusted by matching said timing with said clock of the communication station.

23. The wireless communication apparatus according to claim 14, wherein, if a target beacon transmission time of a beacon transmitting station is later than a target beacon transmission time estimated by the communication station, the clock of the communication station is adjusted by matching said clock with a timing of another station.

24. The wireless communication apparatus according to claim 14, wherein, if a target beacon transmission time of a beacon transmitting station is ahead of a target beacon transmission time estimated by a receiving station, the clock of the receiving station is adjusted by matching the clock with a timing of another station.

25. The wireless communication apparatus according to claim 14, wherein a predetermined period of time is provided for a station that has transmitted a beacon after transmitting said beacon signal to preferentially transmit a packet of data.

26. The wireless communication apparatus according to claim 25, wherein a period of time in which each of said other communication stations executes communication is set based on a predetermined contention control.

27. The wireless communication apparatus according to claim 25, wherein any of said other communication stations that has already recognized a beacon transmission schedule time from another station by referencing an internal clock value transmits information for disabling transmission from a peripheral station for a certain period of time.

28. The wireless communication apparatus according to claim 14, wherein when an attempt is made for transmission immediately after a change from a sleep state to an active state, it is confirmed whether a media is clear for a period of time equivalent to a specified maximum signal length.

29. The wireless communication apparatus according to claim 14, wherein

information associated with said wireless network is information indicative whether an own station recognizes a beacon signal transmitted by another stations at a particular time.

30. The wireless communication apparatus according to claim 14, wherein

said information associated with said wireless network is information indicative that an own station is receiving a beacon signal transmitted by another station at a particular time.

31. The wireless communication apparatus, according to claim 30, wherein

said information indicative that an own station in said network is receiving a beacon signal transmitted at a particular time is information indicated by a relative time with a timer value of the own station.

32. A wireless communication method comprising:

generating a beacon signal to be transmitted from each of a plurality of communication stations, wherein

each of said plurality of communication stations is configured to transmit the beacon according to predetermined timing so as to construct a network, and

each beacon including neighboring beacon information pertaining to beacon transmission times of neighboring communication stations, wherein

each of said plurality of communication stations determines a beacon transmission time based on neighboring beacon information obtained from a beacon signal of another station.